Friday, May 3, 2013

FDOT: Roundabouts Are Now "Preferred" -- Evaluations Mandatory

The Florida Department of Transportation released its 2013 Intersection Design Guide on March 1, adding a new chapter on roundabouts. The opening paragraphs are striking:

Due to substantial safety, operational, and capacity characteristics, roundabouts are an equivalent or better intersection configuration for any new roadway or reconstruction project. Roundabouts shall be evaluated on new construction, reconstruction and safety improvement projects, as well as anytime there are proposed changes in intersection control that will be more restrictive than the existing conditions.

An initial screening shall be conducted at the Preliminary Engineering (PD&E) stage of every project to determine which of the intersections within the project limits will be constructed as roundabouts. The initial screening for applicability of roundabouts is based on traffic volumes. Roundabouts shall be considered the preferred option at intersections where the total projected (design year) entering traffic volumes are up to 25,000 vehicles per day (vpd) for a single-lane, and up to 45,000 vpd for a two lane roundabout.

FDOT is specifying that it does not intend high speed traffic circles:

"On State roads or at intersections with State roads, only modern roundabouts as defined in NCHRP 672 will be allowed."

The recommended design speed is
slightly more than I would want, but a huge improvement over the 45 mph
default speed on the State Highway System:

Roundabouts
should be designed for operating speeds between 20 and 25 mph. The
approaches to the roundabout must be carefully designed to provide
enough deflection to cause motorists to reduce speeds prior to entry.
.... At a minimum, roundabouts should accommodate school buses, moving
vans, garbage trucks, fire trucks, and other emergency vehicles.

The last roundabout simulation I saw at 20 mph functioned poorly because the circulating vehicles whipped around too fast for other vehicles to enter. The irony of roundabouts is that they function more efficiently at slower speeds. Design speeds at 15 mph are more efficient than at 20 or 25 mph.

FDOT now prefers roundabouts because:

Roundabouts by nature encourage lower speeds on the approach to, and within the circulatory roadway, thereby enhancing safety characteristics. The numbers of vehicles that are required to come to a complete stop at a roundabout are significantly less than at a conventional intersection, thereby reducing delay.

FDOT notes that "Roundabouts may be especially useful as a practical solution to skewed intersections." Roundabouts should be considered where a history exists of "fatal and injury crashes" as well as a "pedestrian or bicycle crashes." Roundabouts should also be considered when signalization becomes warranted and as a "context sensitive solution."

The new Intersection Control Guide gives new prominence to protecting pedestrians. In the Roundabout chapter:

Pedestrian features (where applicable) shall be plainly obvious through the use of crosswalks and supplementary signs, and shall include splitter islands sufficiently sized to harbor anticipated pedestrian group sizes (6’ minimum at the crosswalk). Night time illumination is mandatory to increase the visibility of the roundabout and improve sight distance during dark hours.

The treatment for bicyclists is interesting, too, in acknowledging the safety of "taking the lane" as advocated by vehicular cyclists: "At the end of the bicycle lane, the cyclist may either “command the lane” and pass through the circulatory roadway, or divert onto the sidewalk and cross at pedestrian crossings. No bicycle lane markings shall be placed within the circulatory roadway."

ADDITIONAL COMMENT (May 8, 2013)--Here's the language set forth in the Design Guide establishing the steps for priority status for roundabouts:

An initial screening shall be conducted at the Preliminary Engineering
(PD&E) stage of every project to determine which of the intersections within
the project limits will be constructed as roundabouts. The initial screening for
applicability of roundabouts is based on traffic volumes. Roundabouts shall be
considered the preferred option at intersections where the total projected
(design year) entering traffic volumes are up to 25,000 vehicles per day (vpd)
for a single lane, and up to 45,000 vpd for a two-lane roundabout. Minor street
volumes should not be less than 1,500 vpd nor more than 12,000 vpd for a
single-lane, and between 1,500 and 27,000 vpd for a two lane roundabout.
Intersections exhibiting volumes outside these limits may be candidates for
roundabouts subject to an operational analysis. ....

If an
intersection passes the initial screening, an individual isolated operational
analysis of each roundabout shall be performed in compliance with the Highway
Capacity Manual (TRB 2010). A series of roundabouts shall be analyzed using
corridor simulation. .... If a roundabout exhibits equal or better operating and
safety characteristics than a conventional intersection, a roundabout must be
completely advanced through the public involvement (CAP) stage.
....

The cost/benefit analysis shall consider the benefits of crash
and delay reduction of a roundabout in comparison to...a proposed conventional
intersection. The analysis shall also account for the savings in right-of-way
costs...due to the elimination of additional turn and/or auxiliary lanes and
their transitions. If the benefit/cost ratio of a roundabout is greater than
that for a conventional intersection, a roundabout becomes the preferred
alternative.

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About this Blog

I converted my old campaign website into this blog. After Commissioner Boyd appointed me to the Orange County Planning and Zoning Board, I decided to use this blog to discuss issues of importance affecting local government, and to expound on ideas for improving our built environment.

At community meeting after community meeting, citizens express outrage and opposition to new development proposals. Citizens appear before the Planning and Zoning Board, fearful that approval will enable another McDonald's with cartoon architecture or another strip shopping center with a massive, half-empty parking lot in front. Attitudes toward our built environment range mostly from dislike to indifference.

The 1960s-era suburban sprawl model causes traffic congestion, traps our children, the disabled, and elderly in subdivisions without transportation, and produces strip commercial development of poor aesthetic quality. We build sidewalks without shade trees despite Florida's oppresive summer heat. We build subdivisions with 60% or more of each house front devoted to a blank garage. Having turned our roadways into highways, our kids can no longer walk to school.

There is a better way. We are fortunate to have real-world models in Central Florida founded on principles of New (and traditional) Urbanism--Baldwin Park, Celebration, Avalon Park, and Winter Park's Park Avenue--for all to experience. However, our zoning codes make walkable communities illegal (without jumping through innmerable hoops).

I am hopeful this blog will help educate about the benefits of form-based zoning reforms enacted in 2010 in Miami and Denver and under consideration in other cities. The new codes, over the course of decades, can change development configurations from suburban sprawl to walkable urbanism. I compiled the links below to provide you with a multitude of sources. I am hopeful you will join me in advocating a better way.

Rick

"The Legality of Form-Based Zoning Codes," Journal of Land Use... (FL State Univ School of Law)

About Rick

I am a partner with Fishback Dominick in Winter Park, a law firm founded in 1935, where I practice in the areas of business and commercial litigation and, on a selective basis, land use law. I taught Land Use Law as an adjunct professor in the Master of Planning in Civic Urbanism program at Rollins College, in Winter Park, Florida for three years. I previously served as an Orange County Planning and Zoning Commissioner, appointed by District 1 Commissioner Scott Boyd. I reside in Winter Park with my wife, Gabriela, and four terrific kids.

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Below you'll find links to interesting blogs and websites relating to transportation, the law, and the built environment. I don't necessarily agree with all positions taken by the blogging authors, but generally find them well-informed and thoughtful.